An international trial of a new drug for the treatment of the most common form of leukaemia has found it increases survival rates.

The drug leads to more sufferers being clear of the disease within one year, produces fewer side effects and is effective for those with a resistance to chemotherapy.

Scientists at the Royal College of Surgeons in Ireland were involved in the clinical trials of the drug.

Chronic lymphocytic leukaemia is a slow-growing cancer affecting cells that fight disease in bodies.

Leukaemia claims 200 lives in Ireland annually, and CLL accounts for nearly half of the 500 new cases of the disease diagnosed in the country each year.

While conventional treatments for leukaemia are reasonably effective, they can cause severe side effects.

However, a new drug, Ibrutinib, is being hailed as a breakthrough in leukaemia treatment.

It has been trialled on 400 patients internationally, including in Ireland.

Trial results, published in the New England Journal of Medicine, showed survival rates for patients using it rose 10% when compared to the conventional treatments, and patients responded more quickly.

Those trying the drug reported fewer side effects and it was also effective on those whose cancer cells have built up resistance to chemotherapy.

Report co-author Dr Patrick Thornton from the Royal College of Surgeons in Ireland said the new drug represents a complete paradigm shift in leukaemia treatment, which could replace the need for chemotherapy.

Speaking on RTÉ's Morning Ireland, Dr Thornton said: "It works for all CLL, but in particular it works for the most risky version of CLL - people with various chromosomal deletions that normally do very badly or are resistant to chemotherapy, and have a very shortened survival.

"This drug seems to overcome that resistance and is extremely effective with very little side effects."

The consultant haematologist at Beaumont Hospital described the effects of the new drug on some patients as "nothing short of miraculous".

He said Ibrutinib can be given in tablet form to replace the more severe and invasive chemotherapy.

A man who was treated with the new drug has described it as a "magic drug" which miraculously restored his health.

Patrick Kilgallon, a 71-year-old taxi driver from Dublin, was given just eight weeks to live earlier this year after his condition deteriorated.

Speaking on RTÉ's News At One, he said that once he started the drug, his symptoms improved dramatically and he said his health is back to normal.

"Within two weeks I started to improve and by the third week I was back to normal health."

He added: "The lumps went away, the sweating stopped, (I) got stronger, started to put on a little bit of weight and I'm back to normal health and quality of life is perfect. 

"I'm back driving a taxi like I always did, back to normal.

"It gave me my life back. It's a wonderful drug. It's like a magic drug. It's like a miracle that I came back to normal health again."